The present invention in particular relates to the problem of restarting high-pressure discharge lamps, as are used in particular in rear-projection televisions and projectors. After shutdown, such high-pressure discharge lamps require a cooling phase before they can be successfully restarted. As a result, they cannot be switched on again after shutdown as quickly as users of conventional televisions are accustomed to. In the prior art, therefore, such high-pressure discharge lamps are cooled after shutdown for a certain time before a renewed starting attempt is made. The cooling phase generally lasts between 30 seconds and 3 minutes. This long restarting time is particularly undesirable in the case of rear-projection televisions.
US 2002/0135324 A1 has disclosed a method for operating a discharge lamp operated on direct current. The cited document deals with the problem that, when a discharge lamp is switched off, the mercury which has evaporated during operation condenses on one of the two electrodes of the discharge lamp and, as a result, the risk of a short circuit with the other electrode increases. As a solution to this, the cited document proposes cooling the lamp by withdrawing the power in order to thus ensure that the mercury condenses at another point than on the electrode.
As further prior art, mention is made of JP 2004-319193 and JP 2003-109845.